In Germany, approximately 90% of all diabetics, therefore 4.5 million people, are affected by type 2 diabetes, which is usually caused or accompanied by obesity (adiposity). This restricts the quality of life of the affected persons and induces numerous related illnesses. Industrial, emerging, and developing countries are affected in this case in a similar manner. Accordingly, a significant increase of nutrition-related diabetes illnesses is expected worldwide in the coming years.
Present therapies are predominantly directed to a medicinal regulation of the metabolism, there is no causal therapy in the strict sense. In addition to the medicinal metabolic regulation, in adipose patients suffering from diabetes, various methods for adiposity surgery have become established. In these methods, a differentiation is fundamentally made between restrictive (gastric band, gastric reduction, gastric balloon) and malabsorptive methods (bypass, duodenal switch, biliopancreatic diversion), wherein the greatest and most long-lasting successes are achieved by a combination of both method principles.
More recent experiences in adiposity surgery have shown that in particular operation methods which produce a bypass to the duodenum, in addition to the weight reduction, have a direct and immediate effect on the diabetic metabolic state, so that these methods are applied with increasing relevance in the treatment of diabetics.
However, the following facts argue against a large-scale application of operative bypasses of the duodenum:                the severe and irreversible changes of the gastrointestinal tract, which are created by this operation;        the fact that the long-term effects on the metabolism, bone stability, and tumor development are inadequately researched;        that rare, but very severe and sometimes fatal complications can occur due to the interventions;        that the patients require aftercare which is very costly in the long term, with monitoring of metabolic parameters;        that substantial treatment costs arise.        
Because of the complications and costs linked to operative methods, endoscopy has set the goal of developing an implant for the treatment of diabetes and obesity, which, on the basis of duodenal bypass surgery, is based on conducting chyme through the duodenum by means of a tubular prosthesis placed in the duodenum.
The secretions from the pancreas and the gallbladder, which are required for the digestion of food, normally flow to the chyme in the region of the middle duodenum. Clinical studies have been able to show that, by way of an artificially applied transduodenal bypass prosthesis, which accepts the chyme in the stomach and, without mixing with the digestion-active secretions of the duodenum, leads on a direct path into the beginning of the jejunum, the digestion and therefore the resorption of the food components can be reduced, which, in addition to a resulting reduction of the body weight, has direct influence on the blood sugar level and therefore the insulin excretion. The precise mechanism of this phenomenon has not yet been researched, but its effectiveness has been proven.
The constructive design of such bypass tubular prostheses generally provides a mechanism which anchors the device in the region of the gastric outlet or sphincter (pylorus), and which accepts the food as completely as possible in the stomach or immediately adjoining the stomach. This anchoring part is adjoined by a continuing tubular part, which conducts the chyme accepted on the gastric side through the duodenum the into the beginning jejunum. The chyme is advanced in this case by the propulsive movements (peristalsis) of the duodenum in the tube, largely analogous to the natural transportation.
A bypass technology applicable by flexible-endoscopic implantation would be distinguished by the following advantages:                minimal invasiveness;        convenient reversibility, because it can also be removed again in an endoscopic manner; and        cost-effective applicability.        
Various endoscopically placeable duodenal bypass devices with the goal of enteral resorption reduction are presently in testing. The systems are, depending on the structural design, either anchored in a position in the upper duodenum (duodenal bulb) directly adjoining the pylorus distally or they are positioned within the sphincter or extending beyond the pylorus into the stomach.
Regardless of the respective structural type, the anchoring mechanisms have to ensure, on the one hand, that a substantially liquid-tight terminus of the anchoring head unit of the device toward the duodenal wall or the pylorus is achieved, to prevent, as efficiently as possible, food components from passing the duodenum outside the tubular prosthesis and thus restricting its effectiveness. On the other hand, the forces which act by way of the anchoring mechanism on the respective applied organ walls have to be reduced enough that degenerative changes which could result in the course of time in bleeding or perforation, can be precluded. The balance between efficient anchoring and sealing and also organ-compatible placement is not least a challenge because of the special motility of the anatomical structures in the region of the transition from the stomach to the duodenum. The anchoring and sealing component of the bypass has to follow the contractile dynamics in the most compatible possible manner.
For approximately two years, an endoscopically placed, transduodenal tubular prosthesis of approximately 60 cm length, which is anchored using a stent-like metal basket in the upper duodenum within the so-called duodenal bulb, has been the focal point of antidiabetic treatment. This anchoring of the basket is performed by spiked extensions, which dig into the mucosa of the bulb and can be the cause of severe intermittent pain in the patient. The technique requires a permanent intake of stomach-acid-inhibiting medications and can cause complications such as bleeding and perforation of the duodenal wall. In particular, the removal of the implant can be risky because of the laterally protruding metal spikes.
In addition to such stent-based techniques for anchoring the bypass devices which accept the chyme, inter alia, balloon-based and ring-based, transpylorically placed anchor systems are being tested. With these, the pylorus, which marks the anatomical transition from the stomach into the duodenum, is taken between two balloon-like or annular structures in a type of clamping seal. A corresponding transpyloric anchoring by elastically self-erecting, O-ring type elements, which press against the pylorus on the stomach and duodenal sides, is described in U.S. Pat. No. 5,820,584. The two ring elements are integrated into the conducting element and each erect themselves proximally and distally to the sphincter due to the elastic intrinsic tension thereof. The channel-type passage opening of the pylorus is lined by an annular closed membrane unfolded between the rings. A tubular formation for conducting the stomach contents through the duodenum adjoins the ring placed on the duodenal side toward the small intestine. The elastic restoring force of the self-erecting ring components, which is required for the dislocation-secure, transpyloric positioning, and which exerts a permanent small-area force effect on the tissue on both sides of the sphincter, is problematic in the case of such techniques for anchoring. This sustained force action can also result in pressure-related damage or necrosis due to the required long-term application time periods of the transduodenal bypass. In addition, the endoscopic placement of such ring elements is relatively difficult.
US 2011/0004320 A1 describes by way of example a duodenal bypass device based on two tire-like, transpylorically placed fastening elements, which are connected to one another by stranded holding lines. The ring elements each have a rim-like inner tire, on which an elastically expandable balloon tubular element is seated, which expands primarily radially upon filling and thus acts as an anchoring abutment on the gastric and duodenal sides. In this case, upon filling, the balloon-like preformed abutment elements, which press against the pylorus on both sides, enter the state of a toroidal, elastic expansion, having an approximately circular cross section, wherein the pylorus itself remains substantially unloaded, because the completely unfolded buttress elements guide the forces thereof primarily onto the portions of the stomach or the duodenum adjoining the pylorus. The resulting load of these structures can lead to corresponding degenerative damage, as with the above-described, elastically self-erecting ring elements.
To achieve optimum tissue-compatible and organ-compatible, permanent placement of a transpylorically-positioned bypass device, an anchor action would be desirable which reduces the radial force development on the structures adjacent to the pylorus and possibly also guides itself in the axial direction onto the pyloric sphincter.
Furthermore, the transpyloric anchoring should be capable of independently adapting itself as much as possible to functional changes of the sphincter. In the ideal case, the motility of the pylorus should remain unimpaired and/or the pyloric closure and a corresponding deformation of the transpyloric components of the device can take place with the least possible contraction force.
Furthermore, it should be possible in bypasses of the transpyloric type to make the force which loads the pyloric structures and the structures adjoining the pylorus adjustable from outside the body and/or to adapt it to the individual in the course of time.
For an advantageously efficient weight-reducing effect of the device, bypass devices which link the (malresorptive) bypass function with other action principles, for example, a (restrictive) reduction in size of the stomach volume, would also be significant.